Since the nationwide housing reform was initiated in 1988, Chinese cities have sped up transforming themselves from relatively homogeneous societies organized around work-unit compounds towards ones with significant stratification and segregation. Wealthy a??gated communitiesa?? and dilapidated a??migrant enclavesa?? have emerged side by side in many Chinese cities. The provision of affordable housing has become an urgent priority for the central government to find shelters for the low- and middle-income urban households. This thesis examines the affordable housing policy and the socio-spatial changes corresponding to its implementation in Beijing. Data are collected from field surveys and interviews, government policies and census publications. Methods of GIS mapping, descriptive statistics, and spatial autocorrelation tests are used in data analysis.The main findings are that the government intervention in the housing provision system through the affordable housing policy shaped the overall socio-spatial structure at city level which is characterized by a mixed pattern of different kinds of neighborhoods in inner cities and suburbs. The outcome of affordable housing policy in Beijing mainly favors the people with strong ties to the state and in employment. The new experience of homeownership and the protection of their new property rights helped to develop the collective interests and played an important role in the formation of the community. In transitional China, the government still plays an important role in shaping the housing market and determining the housing choice of urban population. Little research on socio-spatial structure has examined the government role in shaping the changing socio-spatial structure in Chinese cities. Using the affordable housing policy and Beijing as an example, this study adds to the existing literature by examining the role of government in shaping the changing socio-spatial structure in urban China.